(A) Field of the Invention
This invention relates to the disposal of chemical wastes and more particularly relates to secure chemical waste landfills.
(B) History of the Prior Art
In the prior art, disposal of chemical waste, and particularly hazardous chemical waste, posed a particularly difficult problem. Originally, there was little concern about the disposal of such chemical waste and they were simply discharged to bodies of water or were buried without concern for subsequent migration of the chemicals.
It later became apparent that care was required in disposing of such wastes. Chemical wastes were then frequently disposed of by placing them in a semi-secure landfill which was lined with water impermeable clay. Such landfills were still not considered adequate for particularly hazardous chemical wastes which were frequently disposed of by constructing concrete vaults in which the waste materials were deposited or by imbedding drums containing the materials in concrete.
Secure landfills were then designed which contained water impervious liners or films in addition to liners of clays or cement layers.
Even these landfills would occasionally leak thus creating leachates which contained chemical waste materials which could enter natural water supplies.
In addition, such landfills had another disadvantage since chemical waste within the landfill could frequently mix thus creating undesirable internal chemical reactions which cause fires, explosions or the creation of even more toxic materials than were originally introduced into the landfill.
Examples of such lined landfills are shown in U.S. Pat. Nos. 4,166,709; 3,732,697 and 3,586,624.
In order to overcome the problem of leachates, leachate collection systems were devised in order to collect leachates from the landfill and store or treat them so that the leachates could not enter natural water supplies. Examples of such leachate collection systems are described in U.S. Pat. Nos. 3,705,851 and 4,171,921. Such a system is also shown in an article in "Newsweek", Mar. 2, 1981 at page 67. In order to avoid mixing of chemicals within the landfill to cause more hazardous products, compartmented landfills were designed.
Even with all of the above described improvements in landfilling of chemical wastes, problems are still apparent. In particular, it has been found that a single leachate system may not be sufficient to collect all of the leachate which might leave the landfill, a single leachate collection still requires that hazardous wastes from all of the compartments in compartmented landfills will be mixed within the leachate collection system; all of the chemical materials collected in a leachate must continue to be treated; rupture of a single synthetic liner can permit increased leaching through the landfill; and chemical materials in adjacent compartments can leak through compartmental walls and still cause undesirable reactions.
Furthermore, in the prior art, monitoring wells were set up to the bottom of the landfill both to determine the composition and quantity of leachate and to permit removal of leachate for treatment. Such monitoring wells had permeable bases which unfortunately would frequently become clogged with sediment and, furthermore, all of the leachate did not necessarily migrate to the base of the well. In addition, such standpipes or wells could easily become damaged as materials were placed in the landfill.